R60 to R75

[AcMedic]

Have the chance to pick up a set of cylinders from an R75. I know that they will bolt right up onto my R60/6 but, can I use my stock carbs? I've also been told that the R60 cam isn't big enough to handle the increase in displacement. Any insight is greatly appreciated.

[Kurt in S.A.]

Clearly the carb internals will need to change since the amount of air being sucked in is now a 750cc engine. I've also heard that you might be disappointed with mating a 750 top end to a 600 bottom end. To really do it right, you would need to change the cam.

Note also that prior to the '76 models, the engine opening is 97mm but changed to 99mm in 1976. So, be sure your cylinders are from matching timeframes.

Kurt in S.A.

[AcMedic]

Thanks Kurt! Sounding more like I should just leave it alone. Nothing wrong with it, was just looking for a little bit more punch.

[Rob Frankham]

Carbs.
The R60 uses 26mm choke piston carbs while the R75 uses 32mm choke CV carbs. The piston carbs will peobably work if rejetted but I would expect it to stifle the top end. You also wouldn't get the benefits of a CV carb. ou can't make the change simply by changing the 'carb internals' to get the full benefit, you would need to swap the carbs.

Cam.
The cam is also differentand this is likely to reduce the benefit of the change.

Heads.
You don't mention the heads. To get the maximum benefit, you'd also have to change the heads.

In conclusion, you would get some benefit by just changing the cylinders and heads, but nowhere near as much as a full conversion. Probably not worth the bother.

Rob

[Rob]

As complete engines are readily available, I would just find a nice one (with carbs?) and wrap the R60 engine and bits up for storage in the back of the garage.

R80 engines are nice, too!